The deletion of the Block manoeuvre seems to have caused the most discussion so far out of any changes from the existing Fate rules. There are two threads that discuss this in detail but I thought I would consolidate clarifications in one place.

So in DFRPG Blocking was a special type of manoeuvre that established passive opposition to a given action or actions equal to the number of shifts obtained on the Block roll.

In Fate Core there are several ways of providing opposition to a given action or actions as follows:

1) Scene Aspects provide Passive or Active Opposition. With the deletion of Barriers from the system these are replaced by Scene Aspects representing barriers between Zones. Other Aspects like "Darkness", "Slippery Floor" etc. also provide constant opposition to certain actions, with the type and level of opposition set by the GM. For instance, "Slippery Floor" might provide Fair passive opposition to any action involving rapid movement, an "Imposing Wall" might provide Great passive opposition to moving between zones. "Moat of Fire" might provide active opposition as an environmental effect.

I note that players can also block certain actions by Creating Advantage. If a player successfully places the "Grappled" aspect on another player or an NPC then that Aspect remains in play until the player lets it go or the NPC manages to Overcome the grapple. This can restrict the actions available to the NPC until he has Overcome the grapple and at the very least allows the player to
make active opposition rolls against his actions (see 2 below).

2) NPCs and Characters can provide active opposition. If a character can arguably be 'in the way' of an action (as often justified by Aspects like 'Grappled') then he can provide active opposition to it. Examples would include: A player who has established that he is providing Covering Fire can provide Active Opposition to movement or to other actions where this would be logical with his Shooting. If someone has mentioned that they're standing next to a door then they can provide Active Opposition to anyone trying to move through the door.

3) NPCs and Characters can Defend to provide opposition. This is usually reserved for cases where they are trying to fend off an 'attack' or negative consequence for themselves. They can Defend Others if they take a full action to do so and sacrifice the usual +2 from a Defend Other action. This is different from option 2, as Leonard Balsera confirms:

"The assumption I probably left out of the text is that being the source of active opposition and taking a defend action aren't the same thing. The former is just a fictional justification - it's no different than the GM setting a difficulty. It just changes who gets
to roll. The latter is specifically intertwined with attack and create advantage as described in the book."

**4) An invoke can add +2 to any opposition you choose, provided you can justify how that aspect is in the way. If that means there would have been no opposition, your invoke provides it at Fair. ﻿

Overcoming Obstacles

Leonard clarifies:

"When an obstacle is overcome, it's *overcome* - whatever considerations need to go into effect to make that legitimate, make
them. That may mean the aspect goes away. That may mean you call ninja bullshit on pulling the same trick over again. It's the same kind of thing as, 'talk about a concession until you find something that has real teeth'."

If the obstacle is not overcome, it's not overcome? I.e. it stays in effect until it's overcome, subject to modification by context.

Leonard says on this subject:

"So, in the cover fire example that's starting to make me feel like hearing "Love Shack" at karaoke, failing means no opportunity to fire, and maybe other costs atop that. Next turn, whatever that person does, firing at the intended target is off-limits. That can choose any other actions, though."